Synergy 2005
SPECIFIC SPINAL
EXERCISE
Three Case Studies Using the MedX Lumbar
Extension Machine
Brian D. Johnston
IART Research
ABSTRACT
The purpose of this research project was to ascertain the effects of specific exercise for the lumbar muscles, by way of
the MedX Lumbar Extension Machine, and relative to previous years of exercise without such a machine. Three
subjects improved lumbar strength significantly, and in one instance, became pain-free within two months although two
years of previous chiropractic and physiotherapy proved ineffective. In two other instances, it became obvious that
traditional exercise, including heavy deadlifts, squats and bent barbell rowing had no positive effect on maintaining or
improving lumbar strength.
INTRODUCTION
Research has indicated emphatically that specific exercise for the lumbar muscles, in an environment that encourages
thigh and pelvic restraint, is both superior and necessary to strengthen those muscles.1,2,3,4,5,6,7,8,9,10 Improvement of
tissue integrity was determined at the University of Florida by way of isolated strength testing dynamometry and dualenergy x-ray absorptiometry (DEXA; a device that measures bone-mineral density and muscle mass).
What most of the above noted research indicated was that improvement can be made, and is made best by way of full
range isolation, as per the use of the MedX Lumbar Extension Machine. Although some research has looked into the
issue of detraining of the lumbar muscles11, this aspect has not been explored to any significant degree.
The purpose of this research paper was to investigate three case subjects and the implications of using the MedX
Lumbar Extension Machine, those subjects being:
1.
A person who experienced muscle strengthening on the MedX Lumbar Extension Machine, but who
discontinued use of the machine for a period of ten years.
2.
A person who is a long-time and serious/competitive fitness enthusiast who had not used the MedX Lumbar
Extension Machine.
3.
A person who incurred a low-back injury from an automobile accident, and who had experienced pain and
weakness as a result.
It is important to look at the differences among potential clients for specific and isolated exercise of the lumbar muscles,
to determine its value both short- and long-term. Doing so may disclose the value of such training, and relative to the
contrary position of non-specific exercise, i.e., today’s so-called ‘functional’ training that incorporates full body
movement to enhance function.
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METHODS
Subjects
Only July 14, 1995, at age 30, Subject 1 (the author) was tested on the medical version of the MedX Lumbar Extension
Machine. A fairly normal strength curve was produced (with only slight deviation from normal at about the midpoint of
the range of motion), and he was able to exert a force of about 475 lbs/215.46 kg at approximately 30-degrees, or the
upright seated position (437 lbs/198.22 kg at 24-degrees and 515 lbs/233.6 kg at 36-degrees). Also, this person was
considered more than two standard deviations above normal for lumbar muscle strength for his age and sex, as shown in
figure 1, with about 255 lbs/115.7 kg being the norm torque output at the 30-degree position. Standard deviations from
normal also are shown on the chart. The different test positions are shown in Figure 2.
Furthermore, Subject 1 is no stranger to heavy, intense exercise, as evidenced in Photos 1-3 (taken at age 40 in July
2005). He has performed heavy bent rows, squats, and deadlifts for several years.
Figure 1: Subject 1 MedX Lumbar Test, July 14, 1995
Average Absolute Isometric Torque: Male 18-35 Years Lumbar
Torque in Foot-pounds
Extension
Flexion
600
Subject 1
500
Norm
400
(-) SD
300
(+) SD
200
100
0
10°
12°
2
3 24°
436°
548°
660°
772°
Angle
Photos 1-3 of Subject 1 at age 40 show the musculature achieved from brief, intense and heavy exercise, but which
exercise did little to maintain or increase the strength of his lumbar muscles.
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Subject 2 (age 52) is a long-time fitness enthusiast, who
competed in bodybuilding, and more recently in
firefighter combat challenges (he set a Canadian record
for age 50-60, by completing the competition in 2
minutes and 5 seconds). With over 30 years of intense
strength training and bodybuilding, as well as continual
training for firefighter conditioning and competition, it
would be expected that his lumbar muscles are very
strong or, at least, above normal.
Subject 3 suffered low back and neck injuries as a result
of an automobile accident more than two years previous.
Earlier work with physiotherapists and chiropractors
provided little pain relief or change in her condition and
function.
Figure 2: The test positions of the medical version of the
MedX Lumbar Extension Machine, from 0-degrees
(extension) to 72-degrees (flexion).
Photo 4: The restraint
mechanism used to
test isometric force at
a position of 30degrees of lumbar
extension. A padded
belt around the upper
back of the subject
was attached to a
nylon strap to the front
of the machine, with a
force censor
connected between.
PROCEDURES
Subjects were restrained in the MedX Lumbar
Extension Machine, at an upright 30-degree position,
and tested isometrically with the Dillon Quantrol Strain
Gauge and a 225 kg capacity load cell located within the
upper body restraining device (rigged between the
machine’s frame and the subject, as shown in Photo 4).
To test muscle torque, subjects for this research project
attempted to extend the spine, but could not move
because of this restraint device, and the legs and hips
could not contribute to force output because of the
restraining mechanisms of the machine. Each isometric
test resulted in 2-seconds to ease into tension, 5-seconds
to produce a maximum effort, and then 2-seconds to
ease out of tension. Future tests to determine muscle
torque change from specific exercise on the MedX
machine included the same restraint setup and
positioning.
A fixed/isometric upright position of 30-degrees for
testing purposes was so chosen for several reasons.
One, to eliminate impact forces (that occur as a result of
dynamic movement). Two, to eliminate the effects of
gravity (i.e., the mass of the torso’s influence on helping
or hindering force output), when the torso is leaned
either forward or backward. Three, to eliminate the
effects of stored energy (stretching and compression of
tissues around the lumbar spine when bent forward or
backward). And four, to replicate an exact position for
every test.
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Most exercise sessions consisted of 5-7 repetitions per subject (a few were as high as 9 repetitions, when the estimated
weight was insufficient), at a cadence of 5-5, for one set of exercise. Exercise varied in frequency, because of
experience, the load used, and intensity of effort. Subject 1 exercised his lumbar muscles every 12 days on average;
Subject 2 exercised his lumbar muscles every 10 days on average; and Subject 3 exercised her lumbar muscles every 7
days on average. Only the lumbar muscles were exercised on this machine since the thighs and hips were restrained
appropriately, as per the machine’s design.
On January 9, 2005 (almost ten years after an initial MedX strength test described previously, and now at age 40),
Subject 1 similarly was restrained in the non-medical version of the MedX Lumbar Extension Machine, and produced
only 274.6 lbs/124.56 kg at a position of 30-degrees; a loss of approximately 42% from when he initially was tested in
1995 (Note: 245 lbs/111 kg is considered normal12 for this subject’s current age and sex, thus suggesting that even with
a loss of strength Subject 1 still was above normal in torque output).
This subject indicated that loss of lumbar strength became apparent over the years, although he had no way to quantify
the effects at the time of this experiment. A loss of function occurred regardless of heavy squats, deadlifts, bent rowing,
and other exercises that would have placed a strain on his lumbar muscles and spine. However, such a strain from those
exercises always was limited to a fixed position in a possible 72-degrees of motion, whereby the subject’s hips, gluteals
and thighs contributed most of the force output to create movement or to maintain stasis during those exercises.
Although a person can and will lose function as he or she ages, various exercise loads (e.g., dips, chest presses, leg
presses, etc.) for this subject remained relatively the same over the past 10 years, as did body composition and girth
measurements. However, research suggests that the lumbar muscles are not like other muscles, and begin to deteriorate
within a person’s second decade of life13,14, whereas that is not the case with other muscles until the third or fourth
decade of life (and only if not exercised to prevent strength and lean mass loss).
The question, then, was whether this subject could rehabilitate his lumbar muscles to their previous function and ability.
(Note: The term “rehabilitate” is valid, although the muscles may not be ‘injured,’ since they reduced a great deal in
function with this subject. Furthermore, a person with less strength initially, and with a slow twitch response [a low
fatigue rate] would not experience such a degree of atrophy in the lumbar muscles, since that fiber type is less
susceptible to atrophy from disuse, but also less inclined to hypertrophy from proper exercise.)
Subject 1 was provided 15 training sessions, which began with 200 pounds for 7 repetitions, and ended with 320 pounds
for 5 repetitions, from January 9, 2005 to July 19, 2005. The number of repetitions reduced from 6-7 to 5 (a 50-second
tension time) once reaching 300 pounds of exercise load, to accommodate his quick-to-fatigue lumbar muscles.
On March 29, 2005, Subject 2 produced an initial force output of 93.9 lbs/42.6 kg, positioned at 30-degrees in the
MedX Lumbar Extension Machine. However, since he was uncertain of what to do exactly (how hard to exert or the
specific method involved in isometric testing), he was retested a week later on April 6, 2005, at which time he produced
a more ‘honest’ and vigorous attempt at 209.8 lbs/95.2 kg (Note: 250 lbs/113.4 kg is considered normal for his age and
sex). Subject 2 was provided 12 training sessions, which began with 120 pounds for 6 repetitions and ended with 260
pounds for 6 repetitions, from March 29, 2005 to July 26, 2005.
Subject 3 was provided one training session at a modest load of 60 pounds before being tested. On December 31st this
subject produced a force of 118.1 lbs/53.6 kg at a position of 30-degrees (Note: 140 lbs/63.5 kg is considered normal for
her age and sex). Subject 3 was provided 12 training sessions, which began with 60 pounds for nine repetitions and
ended with 120 pounds, for six repetitions, from December 24, 2004 to May 3, 2005. Because of time constraints and
personal issues, this subject terminated her treatments and was not re-tested. Nonetheless, a change could be
extrapolated from the collected exercise session data, and which is addressed in the Discussion of this report paper.
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RESULTS
Experimental Data
Subject 1
Subject 2
Subject 3
Pre-test
274.6 lbs/124.56 kg
209.8 lbs/95.2 kg
118.1 lbs/53.57 kg
Beginning Exercise Load
200 lbs/90.72 kg
120 lbs/54.43 kg
60 lbs/27.22 kg
Ending Exercise Load
320 lbs/145.2 kg
260 lbs/117.94 kg
120 lbs/54.43 kg
Number of Exercise
Sessions (1 set each)
15
12
12
Post-test
341.1
334.6 lbs/151.5 kg
NA
Test Improvement
19.5 %
37.3 %
NA
DISCUSSION
Subject 1 showed an improvement of 19.5 %, is 25.25 % stronger than average for his age group and sex, and achieved
the change in a total of 14.75 minutes of exercise time over 15 sessions. His strength has increased, although at age 40
it is difficult at this time to determine if he ever will achieve that which he was capable ten years previous.
Subject 2 showed a marked improvement, and this indicated that years of vigorous, traditional exercise did little to
improve the strength of his lumbar muscles. Nor did the highly ‘functional exercise’ that he did through his firefighter
combat challenge training help him, as current-day fitness trends would suggest. He increased his torque output by
37.3% with direct, isolated exercise, and now is considered 25.3% stronger than average for his age group, whereas he
was 16% weaker than average before his 12 training sessions (that lasted a total of 13-minutes of exercise time).
Subjectively, he has reported far greater function and ability in his firefighter challenge training, and particularly with
the dummy drag event, which event was more stressful on his low back previous to his MedX treatments.
Subject 3 was tested prior to her tenth treatment, and was able to produce 129.3 lbs/58.65 kg of torque. By her twelfth
session she exercised with 120 pounds for 8 repetitions (80-seconds tension time), but unfortunately was not re-tested
thereafter. If we consider that static force is greater than positive dynamic ability (by about 20%), and she was able to
exercise with 120 pounds for multiple repetitions and a relatively long tension time, her isometric torque output likely
would have been at about 140-150 pounds (63.5-68 kg). This would place her functional ability (at that position)
toward ‘normal’ or better for her age and sex. Subject 3 also indicated that her low back pain was nearly non-existent;
noticeable only on occasion. Her total work time over the 12 sessions, for one set each of the exercise was 14 minutes.
CONCLUSIONS
It is evident that to maintain or improve lumbar strength, traditional exercise (whereby the hips and thighs are permitted
to move when exercising the lumbar muscles) provides little effect or benefit. Previous studies have demonstrated as
much, but this research included two advanced trainees, whom have been exercising intensely for over 50 years
combined, and neither of who experienced or demonstrated any positive benefit from traditional exercise. A third
subject, who underwent traditional ‘rehabilitative’ exercise and treatment under the guidance of physiotherapists and
chiropractors, failed to achieve improvement in pain management until she utilized the MedX Lumbar Extension
Machine for this project, a common end result from the author’s perspective and previous medical rehabilitation
experience. Consequently, it seems apparent that strengthening or rehabilitation of the lumbar muscles (if strengthening
is emphasized or required) necessitates exercise that restricts hip and thigh movement, and which is achieved only by
way of the patented MedX Lumbar Extension Machine.
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It may be questioned (and argued) as to why we require such highly isolated exercise since we do not move in like
manner in day-to-day activities. But the fact is that other animals walk on all fours (including primates for the most
part) without spinal problems, and a deterioration of the lumbar muscles in such a situation does not become a concern
as a result. Conversely, walking in a bipedal fashion places the spine in a highly susceptible position for injury, and the
deterioration of the lumbar muscles (as the hips and thighs serve to contribute most to human mobility when
coordinated with spinal movement) therefore necessitates specialized and unique exercise for the lumbar muscles.
ACKNOWLEDGEMENTS
Thanks to MedX (www.CoreSpinalFitness.com) for supplying the Lumbar Extension Machine for this experiment.
Thanks to CSC Force Measurements Inc. (www.cscforce.com) for supplying the necessary force gauge hardware for
this experiment.
REFERENCES
1
Nelson, Brian W., MD, et al. The Clinical Effects of Intensity Specific Exercise on Chronic Low Back Pain: A
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2
Fulton, Michael N., MD., et al. Rehabilitation and Testing: Conservative Treatment for Lower-back and
Cervical Problems. University of Florida, Departments of Medicine and Exercise and Sport Sciences, and
Physiology. Internal research paper.
3
Pollock, Michael L., PhD., et al. Muscle. University of Florida, Departments of Medicine and Exercise and
Sport Sciences, and Physiology. Internal research paper.
4
Panjabi, Manohar, PhD., et al., Yale University School of Medicine and Hokkaido Medical School, Japan. A
Biomechanical Model. Spine. Vol. 14, No. 2, 1989.
5
Leggett, S.H., et al. Effect of Resistance Training on Lumbar Extension Strength. International Journal of
Sports Medicine, 3(9), 1989.
6
Pollock, Michael L., PhD., et al. Effect of Resistance Training on Lumbar Extension Strength. The
American Journal of Sports Medicine, Vol. 17, No. 5, 1989.
7
Graves, James E., PhD., et al. Effect of Training Frequency and Specificity on Isometric Lumbar Extension
Strength. Spine, Vol. 15, No. 6, June 1990.
8
Carpenter, David M., et al. Effect of 12 and 20 Weeks of Resistance Training on Lumbar Extension Torque
Production. Physical Therapy, Vol. 71, No. 8, August 1991.
9
Risch, Sherry V., PhD., et al. Lumbar Strengthening in Chronic Low Back Pain Patients: Physiologic and
Psychological Benefits. Spine, Vol. 18, No. 2, pp 232-238, 1993.
10
Tucci, Jacqueline T., MS, et al. Effect of Reduced Frequency of Training and Detraining on Lumbar
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11
Tucci, Jacqueline T., MS, et al. Effect of Reduced Frequency of Training and Detraining on Lumbar
Extension Strength. Spine, Vo. 17, No. 12, December 1992.
12
Norms for this research project provided by the University of Florida Center for Exercise Science.
13
Parkkola, R, and Kormano, M. Lumbar disc and back muscle degeneration on MRI: correlation to age and body mass.
J Spinal Disorders, 5: 86-92, 1992.
14
Carpenter et al. Low back strength comparisons of elite female collegiate athletes. MedSci Sport Exerc, 26(5): S1: 3,
1994.
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